Improvement in slide-valves for steam-engines



w. FORBES Improvement in Slide-Valves fo'r Steam-Engines- 115,299. Patented MayBOQBi.

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UNITED STATES ISAAC WILLIAM FORBES, o E LA PORTE, .LNDIANA "IMPROVEMENT IN SLIDE-VALVES FOR STEAM-ENGINES.

Specification forming part of Letters Patent No. 115,299, dated May 30,1871.

i nismo wirirm FORBES, of La Porte, in the county of La Porte and ,State of Indiana,

have invented certain `Improvements in Side- Valves for Steam `or Air Engines, of which the following is a specification:

" My invention consists of an equilibriummale slide-valve, the back `of which is inserted in its frame or valve-stem, with steam-tight joint between thetwo to `prevent the passage of steam, all constructed substantially ashereiny after described. Steam is received in the steam-chest by the induction-pipe `outside of the valve or valves which cover the ports.

`Description of the AccompauyingDmwmg. `Figure lis a longitudinal central section of a Idouble valve, `valve-stem, steam-chest, and

valve-seat, withfportions of the cylinder and `ports complete. Fig. `2 isa longitudinal central section of a valve-stem and frame bored y `out for the purpose of receiving the valves. Fig. 3 is the inside portion of one of the valves with the boss'or back extending up, which forms a shankor piston designed to fit in the frame or boss ofthe valve-stem. Fig. 4 is an outside view of the valve and of that part i `which lits on the seat. Fig. 5 is a top view of valve-seat. Fig. `6 is a longitudinal central sec- .,tionof a valvestem, which also forms the ."frame into which the valve is fitted, with one `of the valves in. Fig. 7 isa full side view of `the valve-stem and valves in the frame as f they belong, viewed laterally, as compared withFigs 2 and 6. Fig. 8 is a top view of valves with their frame, stem, and steamchest, with the cover removed, showing their passages. Fig. 9 is the steam-chest cover of Figs. 1 and 8, with induction-ports and exi haust-portywith passages which convey the live and exhaust steam to and through the vcylinder, said ports corresponding with the ports in the' cylinder. Fig. 10 is a central longitudinal section of `a quadruple equilibrium male `slide-valve, with ports in their proper positions in relation to the valves from those described in` previous gures. Two of these valves have holes through them to pre- I vent the `exhaust steam om havingy any effect y to lift them from their face, While the other two have only recessesin the center, like that of a common D. Fig. 11` is an endview of Fig. 10 with the valve-seat removed. Fig. 12 1 is a central longitudinal section of valves removed from the frames, with holes lthrough them, as viewed laterally. Fig. 13 is a top view of Fig. 10 with the valve-seats removed. Fig. 14 is a top view of the seat upon which the valves shown in Figs. 10, 11, 12, and 13 t. Figs. 10, 1l, 12, 13, and 14 all belong to the same cylinders and valves.

In the drawing, A A is the valve-stem, the centery of which forms the frame or ring in which the valves lit. This is bored out true to receive the backs or pistons of the valves.

A is the boss or ring on the valve-stem which forms the frame for the valve. B B is that part ot' the steam-cylinder in which -the ports and steam-passages are. B1 B1 are steampassages in the cylinder which convey steam from the ports. B2 B2 are steam-ports and passages in the steam-chest cover which passV round and through the steam-passages B4 B4 B4, Fig. 8, through the sides of the steamchests to the steam-ports Bl B1 in the cylinder. B3 B3 Vare exhaust-ports in cylinder and steam-chest cover, and steam-passages through the sides of steam-chest, for exhausting. G U

are the valves; G, Shanks; D, pistons upon same to overcome the lift produced by exhaust. These valves tit the mortises in their frames. This frame and valve diler from those in previous figures. H H are 4sides oi' frames in y which these valves belong. When the quadruple valve, as shown in Fig. 10, is used for a single engine, J J would represent the valve-seat of the cylinder 5 J J Vwould represent the valve-seat in the steam-chest cover; in which case K K would extend to one end of the cylinder, while K K would extend to the opposite end oi' the other cylinder. In

this case the ports in the steam-chest must connect with their mates in the cylinder through the sides of the steam-chest, or pipes for that purpose. K K and K1 K1 are induction ports and passages. K2 Kzare exhaust ports and passages.

This valve is moved by an eccentric, or any other valve-gear found necessary or useful, in

the same Way as the common D. It is applicable for the classes of engines for which the ordinary D-valve is used.

Claims. l. The valves G Gr and G G', in combina- I. W. FORBES.

Witnesses W. H. FINCKEL, W. J. PEYToN. 

